Funny no one mentions the SOUND of the amp, just the fact it is big, heavy, rare and "intrinsically awesome". I find this the case with most vintage gear where the "awe power" is from facets that are far removed from its sound. I admit the MX 10000 is a beautiful amp, but it is the rarity, and exclusivity that make it desireable, not necessarily the sound. I have a Bryston 14B SST (2 years young) and a 25 year old Luxman M 05, and the Lux beats the Bryston sonically. Hard to believe but true. But most who lust after the Luxman know of the sound character and the quality of the soundstage (class A helps). But not many lust after it due to its weight, looks or rarity.
I wonder how many vintage pieces have such attachment to them but in actuallity are sonically neutral, bland or average. My guess is the latter. Outside of the vintage community, and the brand name peticularily, you never hear of them at all.... whether they are Yamaha, Rotel, Sansui, Pioneer.....
Makes me wonder where and why the value on vintage electronics is where it is.